Operating Temperature Range .........................-40°C to +125°C
Storage Temperature Range .............................-65°C to +150°C
Junction Temperature ......................................................+150°C
Lead Temperature (soldering, 10s) .................................+300°C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(V
CC
= 1V to 5.5V, T
A
= T
MIN
to T
MAX
, unless otherwise specified. Typical values are at V
CC
= 5V and T
A
= +25°C.) (Note 1)
PARAMETER
Supply Voltage Range
Supply Current
SYMBOL
V
CC
V
CC
≤
5.0V
I
CC
V
CC
≤
3.3V
V
CC
≤
2.0V
V
CC
Reset Threshold Accuracy
Hysteresis
V
CC
to Reset Delay
Reset Timeout Period
V
SRT
Ramp Current
V
SRT
Ramp Threshold
RAMP Threshold Hysteresis
RESET
Output Voltage Low
V
OL
V
TH
V
HYST
t
RD
t
RP
I
RAMP
V
TH-RAMP
V
CC
falling at 1mV/µs
C
SRT
= 1500pF
C
SRT
= 0
V
SRT
= 0 to 0.65V; V
CC
= 1.6V to 5V
V
CC
= 1.6V to 5V (V
RAMP
rising)
V
RAMP
falling threshold
V
CC
≥
1.0V, I
SINK
= 50µA
V
CC
≥
2.7V, I
SINK
= 1.2mA
V
CC
≥
4.5V, I
SINK
= 3.2mA
RESET
Output Voltage High,
Push-Pull
RESET
Output Leakage Current,
Open-Drain
V
CC
≥
1.8V, I
SOURCE
= 200µA
V
OH
V
CC
≥
2.25V, I
SOURCE
= 500µA
V
CC
≥
4.5V, I
SOURCE
= 800µA
I
LKG
V
CC
> V
TH
, reset not asserted
V
CC
≥
1.0V, I
SOURCE
= 1µA
RESET Output Voltage High
V
OH
V
CC
≥
1.8V, I
SOURCE
= 150µA
V
CC
≥
2.7V, I
SOURCE
= 500µA
V
CC
≥
4.5V, I
SOURCE
= 800µA
V
CC
≥
1.8V, I
SINK
= 500µA
RESET Output Voltage Low
V
OL
V
CC
≥
2.7V, I
SINK
= 1.2mA
V
CC
≥
4.5V, I
SINK
= 3.2mA
0.8 x V
CC
0.8 x V
CC
0.8 x V
CC
0.8 x V
CC
0.3
0.3
0.4
V
V
0.8 x V
CC
0.8 x V
CC
0.8 x V
CC
1.0
µA
V
3.00
T
A
= +25°C
T
A
= -40°C to +125°C
V
TH
- 1.5%
V
TH
- 2.5%
80
4.375
0.275
240
0.65
33
0.3
0.3
0.4
V
5.75
CONDITIONS
MIN
1.0
2.5
1.9
1.6
TYP
MAX
5.5
4.2
3.4
2.5
V
TH
+ 1.5%
V
TH
+ 2.5%
V
mV
µs
ms
nA
V
mV
µA
UNITS
V
4 x V
TH
Note 1:
Devices production tested at +25°C. Overtemperature limits are guaranteed by design.
2
Maxim Integrated
MAX6340/
MAX6421–MAX6426
Low-Power, SC70/SOT µP Reset Circuits with
Capacitor-Adjustable Reset Timeout Delay
Typical Operating Characteristics
(V
CC
= 5V, C
SRT
= 1500pF, T
A
= +25°C, unless otherwise noted.)
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX6421/26 toc01
RESET TIMEOUT PERIOD vs. C
SRT
MAX6421/26 toc02
RESET TIMEOUT PERIOD
vs. TEMPERATURE
C
SRT
= 1500pF
RESET TIMEOUT PERIOD (ms)
4.25
MAX6421/26 toc03
MAX6421/26 toc06
4.0
3.5
SUPPLY CURRENT (μA)
3.0
2.5
2.0
1.5
1.0
0.5
0
0
1
2
3
4
5
6
SUPPLY VOLTAGE (V)
T
A
= -40°C
T
A
= +25°C
T
A
= +125°C
10,000
4.30
RESET TIMEOUT PERIOD (ms)
1000
100
4.20
10
4.15
1
0.1
0.001
4.10
0.01
0.1
1
C
SRT
(nF)
10
100
1000
-50
-25
0
25
50
75
100
125
TEMPERATURE (°C)
RESET TIMEOUT PERIOD
vs. TEMPERATURE
MAX6421/26 toc04
MAXIMUM TRANSIENT DURATION
vs. RESET THRESHOLD OVERDRIVE
MAX6421/26 toc05
V
CC
TO RESET DELAY
vs. TEMPERATURE (V
CC
FALLING)
160
V
CC
FALLING AT 1mVμs
150
V
CC
TO RESET DELAY (μs)
140
130
120
110
100
90
80
1000
-50
-25
0
75
50
TEMPERATURE (°C)
25
100
125
600
550
RESET TIMEOUT PERIOD (μs)
500
450
400
350
300
250
200
-50
-25
0
25
50
75
100
C
SRT
= 0
175
150
TRANSIENT DURATION (μs)
125
100
75
50
25
V
TH
= 2.95V
0
RESET OCCURS
ABOVE THE CURVE
125
0
200
400
600
800
TEMPERATURE (°C)
RESET THRESHOLD OVERDRIVE (mV)
POWER-UP/POWER-DOWN
CHARACTERISTIC
MAX6421/26 toc07
NORMALIZED RESET THRESHOLD
vs. TEMPERATURE
MAX6421/26 toc08
NORMALIZED RESET THRESHOLD
V
CC
V
TH
= 1.6V
1.006
1.004
1.002
1.000
0.998
0.996
0.994
1V/div
RESET
1V/div
400μs/div
-50
-25
0
25
50
75
100
125
TEMPERATURE (°C)
Maxim Integrated
3
MAX6340/
MAX6421–MAX6426
Low-Power, SC70/SOT µP Reset Circuits with
Capacitor-Adjustable Reset Timeout Delay
Pin Description
PIN
MAX6340
SOT23
MAX6421
MAX6422
MAX6423
SOT143
SC70
MAX6424
MAX6425
SOT23
MAX6426
SOT23
Set Reset Timeout Input. Connect a capacitor between SRT
and ground to set the timeout period. Determine the period as
follows: t
RP
= 2.73
✕
10
6
✕
C
SRT
+ 275µs with t
RP
in seconds
and C
SRT
in farads.
Ground
Not Internally Connected. Can be connected to GND.
Supply Voltage and Reset Threshold Monitor Input
RESET
changes from high to low whenever V
CC
drops below
the selected reset threshold voltage.
RESET
remains low for
the reset timeout period after V
CC
exceeds the reset
threshold.
RESET changes from low to high whenever V
CC
drops below
the selected reset threshold voltage. RESET remains high for
the reset timeout period after V
CC
exceeds the reset
threshold.
NAME
FUNCTION
1
3
3
5
1
SRT
2
3
4
1
—
2
2
—
1
3
4
2
2, 3
—
5
GND
N.C.
V
CC
5
4
—
4
1
4
RESET
—
—
RESET
Detailed Description
Reset Output
The reset output is typically connected to the reset input
of a µP. A µP’s reset input starts or restarts the µP in a
known state. The MAX6340/MAX6421–MAX6426 µP
supervisory circuits provide the reset logic to prevent
code-execution errors during power-up, power-down,
and brownout conditions (see
Typical Operating
Characteristics).
RESET
changes from high to low whenever V
CC
drops
below the threshold voltage. Once V
CC
exceeds the
threshold voltage,
RESET
remains low for the capacitor-
adjustable reset timeout period.
The MAX6422 active-high RESET output is the inverse
logic of the active-low
RESET
output. All device outputs
are guaranteed valid for V
CC
> 1V.
The MAX6340/MAX6423/MAX6425/MAX6426 are open-
drain
RESET
outputs. Connect an external pullup resis-
tor to any supply from 0 to 5.5V. Select a resistor value
large enough to register a logic low when
RESET
is
asserted and small enough to register a logic high
while supplying all input current and leakage paths
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